Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0039730 (thalassemia)
 10,305 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A 64-year-old man was admitted due to ascites. Laboratory data showed hemoglobin 6.7 g/dl, mean corpuscular volume 82 fl, and ferritin 2,360 ng/ml. Liver biopsy showed hemochromatosis. The diagnosis of beta-thalassemia was suggested by a decreased ratio of beta/alpha-globin synthesis in vitro (0.26). Cloning of the beta-globin gene showed A-to-G mutation in the first base of the ATA box. He was confirmed to be homozygous for this specific allele by beta-gene complex analysis and analysis of Southern blot hybridization of the alpha- and beta-globin genes. His two sons were confirmed to be heterozygous for this allele.
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PMID:Beta(+)-thalassemia with hemochromatosis. 136 99

beta-globin gene haplotypes were determined for 196 normal (beta-A) and 419 thalassaemia (beta-Th) chromosomes of individuals from four different regions of the Indian subcontinent; North-west Pakistan, Gujarat, Punjab and Sindh. Analysis of beta-A and beta-Th haplotypes and haplotype-mutation associations in each regional group along with a consideration of Indian history provided information about the origin and spread of beta-thalassaemia mutations on the Indian subcontinent. The data are consistent with relatively recent and local origins for most beta-thalassaemia mutations. The frequencies of particular alleles differ markedly in various regions and these may be useful population markers. Of the high frequency alleles, intervening sequence 1 (IVS-1) nucleotide 5 (G-C) and codons 41/42 (-CTTT) appear to be older as suggested by multiple haplotype associations and a widespread geographical distribution. The microepidemiology of beta-thalassaemia in this region reflects considerable ethnic diversity, gene flow from population migration and natural selection by malaria infection.
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PMID:Analysis of beta-globin gene haplotypes in Asian Indians: origin and spread of beta-thalassaemia on the Indian subcontinent. 136 88

The prenatal diagnosis of beta-thalassemia in the Udin family, where the parents were the carriers of 2 bp deletion in the codon 8 (-AA) was undertaken using PCR. Five polymorphic restriction endonuclease sites in the beta-globin gene region were tested. They are: 2 HindIII sites in the gamma G and gamma A genes, 2 HincII sites located in the pseudogene and in its 3'-flanking region, and the AvaIII site in the second exon of the beta-globin gene. The heteroduplex analysis was also performed. Two HindIII polymorphic sites were informative and the HincII site in the pseudogene and the AvaII site in the beta-globin gene were partially informative. According to the results of the RFLP analysis, the embryo was heterozygous. The similar result was obtained by heteroduplex analysis.
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PMID:[A case of prenatal diagnosis of beta-thalassemia by polymerase chain reaction]. 136 70

Two mutations in the beta-globin poly(A) signal were identified in Israeli patients with beta +-thalassemia by sequence analysis following PCR. One is a point mutation (AATAAA----AATAAG) and the other is a 5-base-pair deletion (AATAAA----A----). The mutant genes were used to investigate the function of the poly(A) signal in vivo and to evaluate the mechanism whereby these mutations lead to a thalassemic phenotype. Analysis of RNA derived from peripheral blood demonstrated the presence of elongated RNA species in patients carrying either mutation. Other aspects of RNA processing (initiation, splicing) were unimpaired. RNA obtained from the patients carrying the point mutation contained four discrete, extended RNA species, 1500-2900 nucleotides long, which were found to be polyadenylated. Some normal cleavage-polyadenylylation was also observed. The 5-base-pair deletion completely abolished cleavage at the normal site. This deletion mutation resulted in a phenotype of beta +-thalassemia, thus providing evidence that the extended mRNAs are translatable in vivo. Furthermore, additional transcripts, greater than 5 kilobases, presumably mRNA precursors, were found in all RNA samples, including those of nonthalassemic controls. The extended transcripts of the poly(A) mutants, together with the high molecular weight precursors, suggest that the human beta-globin gene transcription unit is significantly longer than previously recognized.
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PMID:Two mutations in the beta-globin polyadenylylation signal reveal extended transcripts and new RNA polyadenylylation sites. 137 96

In normal humans the fetal stage-specific gamma-globin genes are silenced after birth and not expressed in the adult. Exceptions are seen in cases of hereditary persistence of fetal haemoglobin (HPFH). These are clinically important because the elevated levels of gamma-globin can alleviate beta-thalassaemia and sickle cell anaemia. One class of mutations is associated with point mutations in the promoter of the gamma-globin genes (non-deletion HPFH), whereas others seem to be caused by large deletions 3' to the gamma-globin genes. To test whether the point mutation found in the Greek non-deletion HPFH (guanine to adenine at nucleotide position -117) is the cause of the raised gamma-globin levels in the adult stage and is not just a linked polymorphism, we engineered this mutation into a gamma-globin gene. When this gene was introduced into mice, the presence of the -117 mutation results in persistence of gamma-globin expression at a high level and a concomitant decrease in beta-globin expression in fetal and adult mice. We show that these changes correlate with the loss of binding of the transcription factor GATA1 to the gamma-globin promoter, suggesting that it may act as a negative regulator of the gamma-globin gene in adults.
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PMID:A single point mutation is the cause of the Greek form of hereditary persistence of fetal haemoglobin. 137 47

Small deletions of the 5' portion of the beta-globin gene that remove the promoters but stop 3' to the delta-globin gene are recognized as the sole cause of beta-thalassemia with exceptionally high hemoglobin A2 (HbA2) levels. Two patients with beta-thalassemia intermedia and exceptionally high levels of HbA2 (10.4 and 12.0%) were examined. One patient was a combined heterozygote for the -88 C----T and a novel -87 C----A mutation, while the other was homozygous for the -29 A----G beta(+)-thalassemia mutation. The remainder of the beta genes were normal. There was no evidence for deletions involving the 5' portion of the beta gene or the region between the beta and delta genes. Gene mapping studies excluded the possibility of a beta delta-anti-Lepore hemoglobin gene with beta promoters and delta coding sequences. There were no mutations in the promoters of the G gamma or A gamma-globin genes that have been associated with the hereditary persistence of HbF phenotype. The delta-globin gene promoters were normal from codon 17 to position -145 relative to the mRNA capping site. There appears to be considerable heterogeneity of HbA2 and HbF levels in patients who are homozygous or mixed heterozygotes for mutations in the TATA box and other promoter elements of the beta-globin gene. The capacity for proteolysis within the erythrocyte may vary among individuals. The authors hypothesize that in the exceptionally high HbA2 beta-thalassemia intermedia phenotype, proteolysis of superfluous alpha-globin chains is less efficient than in patients with customary levels of HbA2.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Beta-thalassemia intermedia with exceptionally high hemoglobin A2: relationship to mutations in the beta-gene promoter. 138 Feb 6

A large novel deletional beta zero-thalassaemia mutation associated with unusually high levels of haemoglobin A2 in heterozygotes is described in an Australian family. The deletion was characterized by restriction enzyme analysis followed by PCR amplification and sequencing of the breakpoint region. Australian beta zero-thalassaemia extends from 835 basepairs (bp) 5' to the cap site of the beta-globin gene downstream for 12.023 kb. This deletion, similar to previously described deletional beta zero-thalassaemias associated with high Hb A2, removes sequences 5' to the beta-globin gene promoter and emphasizes the functional importance of the 5' beta-globin region in eliciting the unusually high Hb A2 phenotype.
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PMID:Australian beta zero-thalassaemia: a high haemoglobin A2 beta zero-thalassaemia due to a 12 kb deletion commencing 5' to the beta-globin gene. 141 83

The Indian delta beta-thalassaemia, with elevated fetal gamma globin gene expression, was previously found to have a large deletion beginning 1 kb 3' of the (A) gamma globin gene at GenBank HUMHBB coordinate 42151, and extending into a new L1 sequence. We have now determined the 3' breakpoint of this deletion, and in doing so we have extended the known beta-globin gene cluster DNA sequence from its end at 73326 to projected GenBank coordinate 79016. These data show that the deletion is 32.6 kb long, terminating 11 kb 3' of the beta-globin gene. This 3' breakpoint is at 74772, within a 3.4 kb partial L1 repeat at 74263-77665; the Black ((A) gamma delta beta)(0)-thalassaemia also terminates in this L1, at 76508. In addition, two Alu sequences were found, at 73692-73816 and 78171-78441. Among the protein-binding DNA sequence motifs 3' to the Indian delta beta-thalassaemia breakpoint, at 76581/76607 there is a TGATAA/ACACCC pair that binds the erythroid-specific GATA-1 and ubiquitous CACCC-box binding proteins. We hypothesize that elevated fetal haemoglobin may be due to an enhancer or enhancers 3' to the deletion breakpoints and may involve the TGATAA/ACACCC pair.
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PMID:The 32.6 kb Indian delta beta-thalassaemia deletion ends in a 3.4 kb L1 element downstream of the beta-globin gene. 141 24

Characterization of unstable hemoglobins by protein analysis is often difficult. However, it is facilitated by DNA analysis, especially in the case of hyperunstable beta-chain variants, which produce a beta-thalassemia phenotype. We have applied an efficient strategy to the detection of such variants at the DNA level, based on computer-designed denaturing gradient gel electrophoresis (DGGE) of amplified DNA fragments. This approach makes it possible to detect any anomaly in the beta-globin gene. We describe the use of the DGGE method for rapid characterization of beta-chain variants and report a new missense mutation in the beta-globin gene third exon, beta 127 CAG-CGG/Gln-Arg, which is responsible for the synthesis of a highly unstable hemoglobin.
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PMID:Rapid molecular characterization of mutations leading to unstable hemoglobin beta-chain variants. 142 May 7

Short tandem repeats (STRs) are highly informative loci within the human genome, consisting of short nucleotide sequences tandemly repeated in variable numbers. This results in different alleles of variable length. Herein we describe two STRS located 5' to the beta-globin gene. They can be detected by non radioactive methods and may be used to make prenatal diagnosis of beta-thalassemia.
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PMID:Feasibility of prenatal diagnosis of beta-thalassemia using two highly polymorphic microsatellites 5' to the beta-globin gene. 142 47


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